wool: the soft fleece shorn from sheep, spun and woven into cloth
This is the ordinary Hebrew word for wool, the fleece of a sheep once it is shorn and made ready to spin. It names a real, everyday material, not an idea, so it turns up wherever cloth and clothing do: garments inspected for mildew, a capable wife who "seeks wool and flax" and works it with her hands, and the priests forbidden to let it touch them when they serve inside the sanctuary. Alongside linen (פֵּשֶׁת), wool is one of the two great fibers of the ancient world, an animal fiber where linen is a plant one, and the two are named together so often that the law against weaving them into a single cloth needs no explanation.
Because wool is a genuine commodity, it also shows up as wealth. The king of Moab pays Israel a yearly tribute counted in rams and their wool, and the merchants of Tyre trade for the white wool of Damascus. And because good wool is prized for being clean and pale, the Bible reaches for it in word-pictures: snow lies on the ground "like wool," and forgiven sins that were once scarlet will become "as wool." In each of these the point of the comparison is simply the color, wool's soft whiteness, not any hidden meaning in the material itself.
The word stays a single, plain thing throughout. Whether it is fleece on the ground for a sign (גִּזָּה), cloth on the loom, tribute on the road, or an image of what is white and clean, it always means the same wool.